A four-arm star-shaped polylactic acid and its preparation method

Abstract

The present invention relates to the technical field of polylactic acid, and discloses a four-arm star-shaped polylactic acid and a preparation method thereof. Using triethylamine as a catalyst, a pentaerythritol glycidyl ether and an alkyl mercaptan undergo an addition reaction to obtain a tetrahydroxy pentaerythritol intermediate containing a long-chain alkyl group. The tetrahydroxy group is then used as a polymerization site for in-situ ring-opening polymerization with lactide to obtain a four-arm star-shaped polylactic acid containing a long-chain alkyl group. This provides a new and efficient preparation method and strategy for star-shaped polylactic acid. The presence of long alkyl chains in the molecular chains of the four-arm star-shaped polylactic acid can improve the flexibility and crystallization properties of the polylactic acid molecular chains, thereby enabling the star-shaped polylactic acid to have a good glass transition temperature and melting temperature, good crystallization properties, and excellent thermal stability. Furthermore, the long alkyl chains are hydrophobic, which can increase the water contact angle of the polylactic acid and enhance its water resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of polylactic acid, in particular to a four-arm star-shaped polylactic acid and a preparation method thereof. Background Art

[0002] Star-shaped polymers are branched polymers with a central core and multiple linear branches, such as star-shaped polylactic acid, star-shaped polystyrene, star-shaped polyacrylate, etc. They have a special topological structure and unique physical and chemical properties. Their compact structure, high chain density, and low solution viscosity make star-shaped polymers have broad applications in rheology control, thermoplastic elastomers, drug delivery devices, etc.; therefore, the development of new star-shaped polymers has become a research hotspot.

[0003] Polylactic acid is a polymer obtained by polymerization using lactic acid or lactide, a product of microbial fermentation, as the main raw material. The raw material source is extensive and renewable. The production process of polylactic acid is pollution-free, biocompatible, and biosolvable. It is an ideal green polymer material. Star-shaped polylactic acid has multi-arm branching and a network structure and has important applications in drug carrier sustained release and bioengineering. The present invention uses a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group as the core to obtain a novel four-arm star-shaped polylactic acid containing a long-chain alkyl group through ring-opening polymerization. Summary of the Invention

[0004] The invention solves the following technical problems: a novel four-arm star-shaped polylactic acid containing long-chain alkyl groups is prepared, and the crystallization performance and water resistance of the polylactic acid are improved.

[0005] The technical solution of the present invention is:

[0006] A preparation method of a four-arm star-shaped polylactic acid is characterized in that the four-arm star-shaped polylactic acid is prepared by the following method: a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group, lactide and stannous octoate are added to a reaction kettle, the air is replaced by nitrogen, the reaction kettle is evacuated to a vacuum, a reaction is carried out, the reaction is cooled after the reaction, chloroform is added for dissolution, ethanol is added for precipitation, filtering, washing with ethanol and drying to obtain the four-arm star-shaped polylactic acid containing a long-chain alkyl group.

[0007] Preferably, the molar amount of the tetrahydroxypentaerythritol intermediate is 0.1-0.15% of lactide.

[0008] Preferably, the molar amount of stannous octoate is 0.03-0.04% of lactide.

[0009] Preferably, the lactide is any one of D-lactide, L-lactide or D,L-lactide.

[0010] Preferably, the reaction temperature is 130-150° C., and the reaction time is 12-18 hours.

[0011] Preferably, the tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group is prepared by the following method: adding pentaerythritol glycidyl ether, alkyl mercaptan and triethylamine to tetrahydrofuran, concentrating to remove the solvent after the reaction, and washing with acetone to obtain the tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group.

[0012] Preferably, the molar amount of the alkyl mercaptan is 400-550% of the pentaerythritol glycidyl ether.

[0013] Preferably, the alkylthiol has a molecular formula of C n H 2n+1 SH, n is 10, 12, 14, 16 or 18.

[0014] Preferably, the molar amount of triethylamine is 3-7% of pentaerythritol glycidyl ether.

[0015] Preferably, the reaction temperature is 50-70° C. and the reaction time is 6-12 h.

[0016] The beneficial technical effect of the present invention is that: the present invention uses triethylamine as a catalyst to make pentaerythritol glycidyl ether and alkyl mercaptan carry out an addition reaction to obtain a tetrahydroxy pentaerythritol intermediate containing a long-chain alkyl group, and then uses the tetrahydroxy group as a polymerization site to carry out in situ ring-opening polymerization with lactide to obtain a four-arm star-shaped polylactic acid containing a long-chain alkyl group, thereby providing a new and efficient preparation method and strategy for star-shaped polylactic acid.

[0017] The four-arm star-shaped polylactic acid molecular chain contains long alkyl chains, which can improve the flexibility and crystallization properties of the polylactic acid molecular chain, so that the star-shaped polylactic acid has a good glass transition temperature and melting temperature, good crystallization properties and excellent thermal stability; and the long alkyl chains are hydrophobic, which can increase the water contact angle of polylactic acid and enhance its water resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a reaction formula for preparing a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group.

[0019] Figure 2 It is a reaction formula for preparing four-arm star-shaped polylactic acid containing long-chain alkyl groups. DETAILED DESCRIPTION

[0020] The following content provides different embodiments or examples so that those skilled in the art can implement accordingly with reference to the description text. Of course, these are merely examples and are not intended to limit the present invention. The endpoints and any value of the scope disclosed in the present invention are not limited to this accurate scope or value, and these scopes or values ​​should be interpreted as comprising values ​​close to these scopes or values. For numerical ranges, between the endpoint values ​​of each scope, between the endpoint values ​​of each scope and a separate point value, and between the separate point value, can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered as specifically disclosed in this article.

[0021] Example 1

[0022] The preparation method of a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group comprises the following steps: adding 10 mmol of pentaerythritol glycidyl ether, 40 mmol of 1-decanethiol, and 0.3 mmol of triethylamine to tetrahydrofuran, controlling the reaction temperature to 60°C and the reaction time to 12 hours, concentrating to remove the solvent after the reaction, and washing with acetone to obtain a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group.

[0023] The preparation method of a four-arm star-shaped polylactic acid containing a long-chain alkyl group comprises the following steps: adding 2 mmol of a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group, 2 mol of D,L-lactide and 0.7 mmol of stannous octoate into a reactor, replacing the air with nitrogen, and then evacuating to a vacuum state to carry out a reaction at a temperature of 130° C. for 18 hours. After the reaction, the reactor is cooled, chloroform is added for dissolution, and ethanol is added for precipitation. The reactor is filtered, washed with ethanol, and dried to obtain a four-arm star-shaped polylactic acid containing a long-chain alkyl group.

[0024] Example 2

[0025] The preparation method of a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group comprises the following steps: adding 10 mmol of pentaerythritol glycidyl ether, 48 mmol of dodecanethiol, and 0.5 mmol of triethylamine to tetrahydrofuran, controlling the reaction temperature to 70°C and the reaction time to 6 hours, concentrating to remove the solvent after the reaction, and washing with acetone to obtain a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group.

[0026] The invention discloses a method for preparing a four-arm star-shaped polylactic acid containing a long-chain alkyl group: 3 mmol of a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group, 2 mol of D-lactide and 0.8 mmol of stannous octoate are added to a reactor, the air is replaced by nitrogen, and then the reactor is evacuated to a vacuum for reaction at a temperature of 150° C. for 12 hours. After the reaction, the reactor is cooled, chloroform is added for dissolution, and ethanol is added for precipitation. The reactor is filtered, washed with ethanol and dried to obtain a four-arm star-shaped polylactic acid containing a long-chain alkyl group.

[0027] Example 3

[0028] The preparation method of a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group comprises the following steps: adding 10 mmol of pentaerythritol glycidyl ether, 55 mmol of tetradecanethiol, and 0.7 mmol of triethylamine to tetrahydrofuran, controlling the reaction temperature to 50°C and the reaction time to 6 hours, concentrating to remove the solvent after the reaction, and washing with acetone to obtain a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group.

[0029] The invention discloses a method for preparing a four-arm star-shaped polylactic acid containing a long-chain alkyl group: 3 mmol of a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group, 2 mol of L-lactide and 0.8 mmol of stannous octoate are added to a reactor, the air is replaced by nitrogen, and then the reactor is evacuated to a vacuum state for reaction at a temperature of 140° C. for 12 hours. After the reaction, the reactor is cooled, chloroform is added for dissolution, and ethanol is added for precipitation. The reactor is filtered, washed with ethanol and dried to obtain a four-arm star-shaped polylactic acid containing a long-chain alkyl group.

[0030] Example 4

[0031] The preparation method of a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group comprises the following steps: adding 10 mmol of pentaerythritol glycidyl ether, 40 mmol of hexadecanethiol, and 0.3 mmol of triethylamine to tetrahydrofuran, controlling the reaction temperature to 60°C and the reaction time to 12 hours, concentrating to remove the solvent after the reaction, and washing with acetone to obtain a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group.

[0032] The preparation method of a four-arm star-shaped polylactic acid containing a long-chain alkyl group comprises the following steps: adding 2.5 mmol of a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group, 2 mol of D,L-lactide and 0.7 mmol of stannous octoate into a reactor, replacing the air with nitrogen, and then evacuating to a vacuum state to carry out a reaction at a temperature of 140° C. for 12 hours. After the reaction, the reactor is cooled, chloroform is added for dissolution, and ethanol is added for precipitation. The reactor is filtered, washed with ethanol, and dried to obtain a four-arm star-shaped polylactic acid containing a long-chain alkyl group.

[0033] Example 5

[0034] The preparation method of a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group comprises the following steps: adding 10 mmol of pentaerythritol glycidyl ether, 48 mmol of octadecanethiol, and 0.7 mmol of triethylamine to tetrahydrofuran, controlling the reaction temperature to 70°C and the reaction time to 6 hours, concentrating to remove the solvent after the reaction, and washing with acetone to obtain a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group.

[0035] The preparation method of a four-arm star-shaped polylactic acid containing a long-chain alkyl group comprises the following steps: adding 2 mmol of a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group, 2 mol of D,L-lactide and 0.6 mmol of stannous octoate into a reactor, replacing the air with nitrogen, and then evacuating to a vacuum state to carry out a reaction at a temperature of 150° C. for 18 hours. After the reaction, the reactor is cooled, chloroform is added for dissolution, and ethanol is added for precipitation. The reactor is filtered, washed with ethanol, and dried to obtain a four-arm star-shaped polylactic acid containing a long-chain alkyl group.

[0036] Example 6

[0037] The preparation method of a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group comprises the following steps: adding 10 mmol of pentaerythritol glycidyl ether, 48 mmol of octadecanethiol, and 0.5 mmol of triethylamine to tetrahydrofuran, controlling the reaction temperature to 60°C and the reaction time to 6 hours, concentrating to remove the solvent after the reaction, and washing with acetone to obtain a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group.

[0038] The invention discloses a method for preparing a four-arm star-shaped polylactic acid containing a long-chain alkyl group: 2 mmol of a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group, 2 mol of L-lactide and 0.6 mmol of stannous octoate are added to a reactor, the air is replaced by nitrogen, and then the reactor is evacuated to a vacuum state for reaction at a temperature of 140° C. for 12 hours. After the reaction, the reactor is cooled, chloroform is added for dissolution, and ethanol is added for precipitation. The reactor is filtered, washed with ethanol and dried to obtain a four-arm star-shaped polylactic acid containing a long-chain alkyl group.

[0039] Example 7

[0040] The preparation method of a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group comprises the following steps: adding 10 mmol of pentaerythritol glycidyl ether, 48 mmol of octadecanethiol, and 0.7 mmol of triethylamine to tetrahydrofuran, controlling the reaction temperature to 70°C and the reaction time to 6 hours, concentrating to remove the solvent after the reaction, and washing with acetone to obtain a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group.

[0041] The invention discloses a method for preparing a four-arm star-shaped polylactic acid containing a long-chain alkyl group: 2 mmol of a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group, 2 mol of D-lactide and 0.6 mmol of stannous octoate are added to a reactor, the air is replaced by nitrogen, and then the reactor is evacuated to a vacuum state for reaction at a temperature of 150° C. for 15 hours. After the reaction, the reactor is cooled, chloroform is added for dissolution, and ethanol is added for precipitation. The reactor is filtered, washed with ethanol and dried to obtain a four-arm star-shaped polylactic acid containing a long-chain alkyl group.

[0042] The crystallization properties of four-arm star-shaped polylactic acid were tested using differential scanning calorimetry (DSC) in a nitrogen atmosphere at a flow rate of 40 mL / min.

[0043]

[0044] The water contact angle of polylactic acid was measured using an optical contact angle tester.

[0045]

[0046]

[0047] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details of the above embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the scope of protection of the present disclosure.

Claims

1. A method for preparing a four-arm star-shaped polylactic acid, characterized in that: The four-arm star-shaped polylactic acid is prepared by the following method: adding a tetrahydroxypentaerythritol intermediate containing a long-chain alkyl group, lactide, and stannous octoate into a reaction kettle, replacing the air with nitrogen, then evacuating to a vacuum, reacting, cooling after the reaction, adding chloroform to dissolve, then adding ethanol to precipitate, filtering, washing with ethanol, and drying to obtain a four-arm star-shaped polylactic acid containing a long-chain alkyl group; The tetrahydroxy pentaerythritol intermediate containing a long-chain alkyl group is prepared by the following method: adding pentaerythritol glycidyl ether, alkyl mercaptan, and triethylamine to tetrahydrofuran, concentrating to remove the solvent after the reaction, and washing with acetone to obtain the tetrahydroxy pentaerythritol intermediate containing a long-chain alkyl group; in the preparation method of the tetrahydroxy pentaerythritol intermediate containing a long-chain alkyl group, the reaction temperature is 50-70°C and the reaction time is 6-12 hours; The molecular formula of the alkylthiol is C n H 2n+1 SH, n is 10, 12, 14, 16 or 18.

2. The method for preparing the four-arm star-shaped polylactic acid according to claim 1, wherein: The molar amount of the tetrahydroxypentaerythritol intermediate is 0.1-0.15% of lactide.

3. The method for preparing the four-arm star-shaped polylactic acid according to claim 1, wherein: The molar amount of stannous octoate is 0.03-0.04% of lactide.

4. The method for preparing the four-arm star-shaped polylactic acid according to claim 1, wherein: The lactide is any one of D-lactide, L-lactide or D,L-lactide.

5. The method for preparing the four-arm star-shaped polylactic acid according to claim 1, wherein: The reaction temperature is 130-150° C. and the reaction time is 12-18 h.

6. The method for preparing the four-arm star-shaped polylactic acid according to claim 1, wherein: The molar amount of the alkyl mercaptan is 400-550% of the pentaerythritol glycidyl ether.

7. The method for preparing the four-arm star-shaped polylactic acid according to claim 1, wherein: The molar amount of triethylamine is 3-7% of pentaerythritol glycidyl ether.

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